Reject images w/o DateTimeOriginal

[nathanielrindlaub]

Very rarely (but sometimes, e.g. if the image has been modified or edited in some other program) images don't have DateTimeOriginal tags in their EXIF data, and when ingest-image encounters that it throws the following error:

ERROR   Invoke Error    
{
    "errorType": "TimestampParseError",
    "errorMessage": "Failed to parse token \":\" at position [0] in timestamp \"undefined\" with format \"%Y:%m:%d %H:%M:%S\": String literal \":\" not matched.",
    "reason": "String literal \":\" not matched.",
    "format": "%Y:%m:%d %H:%M:%S",
    "timestamp": "undefined",
    "token": {
        "string": ":"
    },
    "index": 0,
    "message": "Failed to parse token \":\" at position [0] in timestamp \"undefined\" with format \"%Y:%m:%d %H:%M:%S\": String literal \":\" not matched.",
    "stack": [
        "TimestampParseError: Failed to parse token \":\" at position [0] in timestamp \"undefined\" with format \"%Y:%m:%d %H:%M:%S\": String literal \":\" not matched.",
        "    at TimestampParser.parseStringToken (/var/task/node_modules/strtime/dist/strtime.js:1213:23)",
        "    at TimestampParser.parse (/var/task/node_modules/strtime/dist/strtime.js:1186:22)",
        "    at strptime (/var/task/node_modules/strtime/dist/strtime.js:106:27)",
        "    at Task.convert_datetime_to_ISO (file:///var/task/task.js:273:31)",
        "    at Task.enrich_meta_data (file:///var/task/task.js:285:36)",
        "    at Task.process_image (file:///var/task/task.js:119:25)",
        "    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)",
        "    at async Task.control (file:///var/task/task.js:78:21)",
        "    at async Runtime.handler (file:///var/task/task.js:343:5)"
    ]
}

I am open to ideas on alternative ways to handle this situation, but perhaps a first step is rejecting them, writing the error to the image errors collection (see #42, and moving them to the dead-letter bucket).